Assessment of natural radionuclides and its radiological hazards from tiles made in Nigeria

Author’s Accepted Manuscript Assessment of Natural Radionuclides and Its Radiological Hazards from Tiles Made in Nigeria E.S Joel, Omeje Maxwell, O.O Adewoyin, Ehieromosele Cyril, Zaidi Embong, Mohamad Alam Saeed www.elsevier.com/locate/radphyschem

PII: DOI: Reference:

S0969-806X(17)30840-X https://doi.org/10.1016/j.radphyschem.2017.11.003 RPC7686

To appear in: Radiation Physics and Chemistry Received date: 1 August 2017 Revised date: 13 October 2017 Accepted date: 7 November 2017 Cite this article as: E.S Joel, Omeje Maxwell, O.O Adewoyin, Ehi-eromosele Cyril, Zaidi Embong and Mohamad Alam Saeed, Assessment of Natural Radionuclides and Its Radiological Hazards from Tiles Made in Nigeria, Radiation Physics and Chemistry, https://doi.org/10.1016/j.radphyschem.2017.11.003 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Assessment of Natural Radionuclides and Its Radiological Hazards from Tiles Made in Nigeria E.S Joel1*, Omeje Maxwell1, O.O Adewoyin1, Ehi-eromosele Cyril2, Zaidi Embong3, Mohamad Alam Saeed 1 2 3

4

Department of Physics, Covenant University Ota, Nigeria

Department of Chemistry, Covenant University Ota, Nigeria

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, Skudai, Johor, Malaysia

*Corresponding author email address: [email protected] Abstract Activity concentration of 10 different brands of tiles made in Nigeria were analyzed using High purity Germanium gamma detector and its hazard indices such as absorbed dose rate, radium equivalent activity, external Hazard Index (Hex), internal Hazard Index (Hin), Annual Effective Dose (mSv/y), Gamma activity Index (Iγ) and Alpha Index (Iα) were determined. The result showed that the average activity concentrations of radionuclides (226Ra,

232

Th and

40

K) content

are within the recommended limit. The average radium equivalent is within the recommended limit of 370 Bq/kg. The result obtained further showed that the mean values for the absorbed dose rate (D), external and internal hazard index, the annual effective dose (AEDR) equivalent, gamma activity index and Alpha Index were: 169.22 nGyh-1, 0.95 and 1.14, 1.59 mSv/y, 1.00 Sv yr-1 and 0.34 respectively. The result established that radiological hazards such as absorbed dose rate, internal hazard, annual effective dose rate, gamma activity index and Alpha Index for some samples are found to be slightly close or above international recommended values. The result for the present study was compared with tiles sample from others countries, it was observed that the concentration of tiles made in Nigeria and other countries are closer, however recommends proper radiation monitoring for some tiles made in Nigeria before usage due to the long term health effect. Keywords: Radioactivity concentrations, radiological hazards, tiles 1. Introduction

The exposure of human beings to ionizing radiation from natural sources is a continuing and inescapable feature of life on earth. For most individuals, this exposure exceeds that from all man-made sources combined. There are two main contributors to natural radiation exposures: high-energy cosmic ray particles incident on the earth's atmosphere and radioactive nuclides that originated in the earth's crust and are present everywhere in the environment, including the human body itself (USCEAR, 2000). Many exposures to natural radiation sources are modified by human practices. In particular, natural radionuclides are released to the environment in mineral processing and uses, such as phosphate fertilizer production and use and fossil fuel combustion, causing enhanced natural radiation exposures (UNSCEAR, 2000). Natural radioactivity in soils comes from

238

U and

232

Th series and natural

40

K. Uranium occurs in

minerals such as pitchblende, uraninite, etc. It is also found in phosphate rock, lignite and monazite sands. Radon is formed from the decay of radium. The interested radionuclides in the research about environmental radioactivity are

226

Ra,

232

Th and 40K (Ademola and Farai, 2006),

among which 226Ra is a radionuclide in the 238U series and 232Th is the first member in the 232Th series. The natural radionuclides in building materials are responsible for the external and internal radiation exposures of individuals living in dwellings (Ali et al., 1996; Faheem et al.,2008; Ghosh et al.,2008; Turhan, 2008; Damla et al.,2011). Since the natural radionuclides are not uniformly distributed, the knowledge of the natural radioactivity in building materials is important for the determination of population exposure to radiation, as most of the residents spent 80–90% of their life time indoors (Lu, 2005; Ghosh et al.,2008). Building materials are derived from both natural sources (e.g. rock and soil) and waste products (e.g. phosphogypsum, alum shale, coal flyash, oil shale ash, etc) and also from industry by-products (e.g. power plants, phosphate fertilizer and oil industry) (Baykara et al., 2011). The concentrations of and

40

226

Ra,

232

Th

K in building materials such as tiles vary depending on the local geological and

geographical conditions as well as geochemical characteristics of those materials (Iqbal et al., 2000; Ghosh et al.,2008; Turhan, 2008). Therefore, it is important to measure the concentration of radionuclides in all the tiles used for building that was made in Nigeria and to estimate the radiological hazards to human health.

2. Materials and Methods 2.1 Preparation of Samples

10 samples of various tiles which were produced in Nigeria were used for this study. These tiles were purchased from Nigerian commercial market. This is shown in Table 1 with their sample names and ID (size). Initial labeling and cataloguing was done for easy identification. The tiles were broken into smaller pieces so as to allow further processing. All the samples were crushed using the Pascall Engineering Lab milling machine to pulverizable size. After each tile sample was crushed, the crusher or lab milling machine was thoroughly cleaned with high pressure blower (Wolf from Kango Wolf power tools, made in London, type 8793 and serial no: 978A) before the next sample was crushed. This whole process was repeated until all the samples were completely crushed into powder. The pulverizer used is the disk ‘grinder/pulverizer’ by Christy & Norris Limited. After each pulverizing process, the machine was cleaned properly and blown with high pressure blower to avoid cross contamination of the samples. A very fine power was achieved from the pulverized samples, but for homogeneity, a 250 µm sieve size was used and 1 kg of the sieved sample was weighed out. It was then placed in polythene nylon and labeled accordingly. High density polyethylene bottles (HDPB) were used to package the samples for radioactivity study. The bottles were washed with water and detergent and then rinsed six times with ordinary borehole water before finally rinsing with distilled water. The sieved samples of tiles that were contained in each bottle weighed 200 g. 2.2 Gamma Spectrometric Analysis of the Selected Samples The tiles produced in Nigeria of different brands was purchased from different suppliers, were prepared according to IAEA TRS-295 (IAEA, 1989). The samples were put in a plastic beaker container sealed for four (4) weeks secular equilibrium. Analysis of the samples were conducted in Canada (Activation Laboratory System) using High Purity Germanium detector, Canberra LynxTM Digital Signal Analyzer (DSA), a 32 K channel integrated signal analyzer and a topopening lead shield (4” lead, copper/tin liner) to prevent high background counts with 50 % relative efficiency and resolution of 2.1 keV at 1.33 MeV gamma energy of 60Co. The Genie-2K V3.2 software locates and analyzes the peaks, subtracts background, identifies the nuclides. The efficiency curves for this analysis were corrected for the attenuation and self-absorption effects of the emitted gamma photons. CAMET and IAEA standards (DL-1a, UTS-2, UTS-4, IAEA-372 and IAEA-447) were used for checking the efficiency calibration of the system. For the activity measurements, the samples were counted for 86,400 seconds with the background counts subtracted from the net count. The minimum detectable activity of the detector was determined

with a confidence level of 95 %. The uncertainty errors were estimated keeping into account the associated errors from gamma courting emission probability and efficiency calibration standard of the system. The progeny of radium, 214Bi and 214Pb emits gamma line 609 keV, 934 keV, 2204 keV, 1764 keV and 351 keV, 295 keV were used but the resolution of radium was from the emission of 1764 keV since it has low self-attenuation effect at high energy. Since 208

be directly detected, the estimated activity via its progeny

Tl and

232

Th cannot

228

Act using 2614.53 keV,

(35.63%) 583 keV (30.3%) and 911 keV, 338 keV, 463 keV. The gamma line of 1461 keV (10.7%) was used to resolve 40K. Table 1 Tiles of different types produced in Nigeria

Sample Name

Country

Sample size (mm)

BN Ceramics

Nigeria

60X60

PNT Ceramics

Nigeria

30X30

Golden Crown Ceramics

Nigeria

25X30

Royal Ceramics

Nigeria

40X40

Royal Crown

Nigeria

30X30

Goodwill Super Polish

Nigeria

60X60

NISPRO

Nigeria

40X40

Goodwill Vitrified

Nigeria

40X40

PNT Vitrified

Nigeria

25X40

Golden Crown

Nigeria

30X30

3. Result and Discussions 3.1 Determination of Radioactivity Concentration Table 2 presents the radioactivity concentrations of

226

232

Ra,

Th, and

40

K for the tiles samples

produced in Nigeria and their average value respectively. The observed activities concentration of the radionuclides content in the tiles ranged from 27 - 241 Bq/kg for 226Ra, 41 - 461 Bq/kg for 232

Th and 270 - 860 Bq/kg for 40K respectively. The PNT ceramics tiles of size 30X30 mm was

noted to have the highest value of 241 Bq/kg for 461 Bq/kg for

232

Th and 860 Bq/kg for

40

226

Ra; NISPRO tile of size 40X40 mm have

K respectively. The lowest values of 27, 41 and 270

Bq/kg are found to be for tiles samples BN ceramics, Royal crown and Goodwill super polish while mean value of the radionuclides

226

Ra,

232

Th, and

40

K

are 68. 2, 173.9 and 490 Bq/kg

respectively. These average values were found to be within international reference value when compared with IAEA (2003) report. This present study was compared with others countries as reported elsewhere using the activity concentrations measured and are presented in Table 3. In contrast, it can be observed that the concentration of tiles in Nigeria and other countries are closer for 226Ra, 232Th and 40K radionuclides as reported by Amin and Naji (2014) except for 40K which is a little bit higher but still within the recommended value.

3.2 Radiological Assessment 3.2.1 The Absorbed Dose Rate In this present study, the absorbed dose rates obtained from the calculated activity concentrations are shown in Table 4. The total air absorbed dose rate received in an open air 1 m above the ground due to gamma emission from the radionuclides of

226

Ra,

232

Th and

40

K in BqKg-1

available in an environment is calculated using Equation (1) (UNSCEAR, 1998; UNSCEAR, 2000)





D nGyh 1  0.642C Ra  0.604CTh  0.0417C k 80nGyh 1

(1)

Considering the absorbed dose rates presented in Table 4, it can be observed that the highest value of 352.51nGyh-1 was reported in NISPRO tiles whereas the lowest value of 70.61nGyh-1 was noted in Goodwill super polish tile. Comparing the absorbed dose rate in this present study with the standard value of 80 nGyh-1 recommended by UNSCEAR (1998), the highest value obtained in this present study is higher by a factor of 4.4.

3.2.2 Determination of Radium equivalent (Raeq) The level of radionuclides from

226

Ra,

232

Th and

40

K in the analyzed building materials is non-

uniformly distributed. The Raeq activity of the measured radionuclides is used to compare the activity of each of

226

Ra,

232

Th and

40

K contents in the building materials. Raeq with unit as

BqKg-1 was calculated using Equation (2).

Raeq  AC RA  1.43CTh  0.077 AC K

(2)

where ACRA, ACTh and ACK are the activities concentration of 226Ra, 232Th and 40K measured in BqKg-1 respectively. This radium equivalent activity defines the weighted sum of the individual activities of 226Ra, 232Th and 40K with the idea that for 226Ra, Raeq is 10 Bq kg−1, for 232Th, Raeq is 7 Bq kg−1 and for

40

K, Raeq is 130 Bqkg−1. The maximum value of Raeq in tiles materials

must be less than 370 Bq kg−1 as recommended by UNSCEAR (1998) and UNSCEAR (2000). The radium equivalent activity values obtained from this present study varies from 138.44 to 784.95 BqKg-1with the highest value of 784.95 BqKg-1 reported in NISPRO whereas the lowest value of 138.44 BqKg-1 was noted in Goodwill super polish tile and the mean value of 354.56 BqKg-1 is noted. It can be observed that some tiles samples such as PNT Ceramics (30X30), NISPRO, Goodwill Vitrified and PNT Ceramics (25X40) have the Raeq value that exceeds the recommended limit of 370 BqKg-1 by UNSCEAR (1998) and UNSCEAR (2000) as presented in Table 4.

3.2.3. Evaluation of External Hazard Index The gamma ray radiation hazards index due to the specified radionuclides were assessed by external radiation hazard and was calculated using Equation (3) according to UNSCEAR (2000). C    CTh   CK  H ex   Ra      370 259 4810      

(3)

where, CRa , CTh and CK are the average activity concentrations of

226

Ra,

232

Th and

40

K in Bqkg‒1

respectively. For the radiation hazard to be acceptable, it is recommended that the Hex be less than unity. The estimated Hex for all the samples varies from 0.37 to 2.11with highest value noted in NISPRO tile whereas the lowest value reported in Goodwill super polish. This highest value from the present study is higher than the recommended value of ≤ 1 according to UNSCEAR (2000) by a factor of 5.7.

3.2.4 Determination of Internal Hazard Index The hazard which is defined in relation to internal hazard is represented by Hin respectively and can be determined using equations (4) (Beretka and Mathew, 1985): H in   

C Ra

   CTh   CK  185   259   4810 

(4)

where CRa, CTh and CK are activity concentrations of 226Ra, 232Th and 40K, respectively in Bq/kg. For the safe use of a building material such as tiles for decorative purposes in construction, Hin should be less than unity. The calculated values of Hin for tile samples used are shown in Table

4. The values ranged between 0.53 and 2.28 and the mean values of 1.14 for internal hazard (Hin). The obtained results for Hin for PNT ceramic, NISPRO, Goodwill super polish and PNT ceramic (25X40) tiles are above recommended limit of unity. The results for other tile samples are less than unity and are in agreement with the recommended international values.

Table 2. Radioactivity concentration in tiles made in Nigeria in (Bq/kg) Sample Name

Sample size

Activity Concentration (Bq/kg) 226

Ra

232

Th

40

K

BN Ceramics

60X60

37.5

101.5

670.0

PNT Ceramics

30X30

241.0

77.5

510.0

Golden Crown Ceramics

25X30

49.5

57.5

460.0

Royal Ceramics

40X40

65.5

44.0

390.0

Royal Crown

30X30

51.5

41.0

440.0

Goodwill Super Polish

60X60

44.0

51.5

270.0

NISPRO

40X40

59.5

461.0

860.0

Goodwill Vitrified

40X40

70.5

445.5

540.0

PNT Vitrified

25X40

35.5

346.5

370.0

Golden Crown

30X30

27.0

113.0

390.0

Mean Value

68. 2

173.9

490.0

Table 3. Comparison of Radioactivity concentration in tiles made in Nigeria with other tiles from other countries 226

BN Ceramics

Nigeria

37.5

101.5

670.0

Present study

PNT Ceramics

Nigeria

241.0

77.5

510.0

Present study

Nigeria

49.5

57.5

460.0

Present study

Royal Ceramics

Nigeria

65.5

44.0

390.0

Present study

Royal Crown

Nigeria

51.5

41.0

440.0

Present study

Nigeria

44.0

51.5

270.0

Present study

NISPRO

Nigeria

59.5

461.0

860.0

Present study

Goodwill Vitrified

Nigeria

70.5

445.5

540.0

Present study

PNT Ceramics

Nigeria

35.5

346.5

370.0

Present study

Golden Crown

Nigeria

27.0

113.0

390.0

Present study

Taulell

Italy

135

487

547

Amin and Naji, 2014

Cerypsa

Spain

92.3

427

816

Amin and Naji, 2014

Alfujera

UAE

60

13

463

Amin and Naji, 2014

Atlas

India

452

227

237

Amin and Naji, 2014

Refan

Yemen

125

21

376

Amin and Naji, 2014

Meran

China

61

0

24

Amin and Naji, 2014

0

267

258

Amin and Naji, 2014

114

47

223

Amin and Naji, 2014

Ceramics

Goodwill Super Polish

Al jouda Roman

Kingdom of Saudi Arabia Indonesia

Th

40

Country

Golden Crown

Ra

232

Sample Name

K

Reference

Table 4. The Absorbed Dose, Radium Equivalent (Raeq), External Hazard Index (Hex) and Internal Hazard Index (Hin) Sample Name

Sample size

Raeq(Bq/kg)

D(nGyh-1)

Hex

Hin

BN Ceramics

60X60

234. 24

113.32

0.63

0.73

PNT Ceramics

30X30

391.09

222.79

1.06

1.71

25X30

167.15

85.69

0.45

0.59

Royal Ceramics

40X40

158.45

84.89

0.43

0.61

Royal Crown

30X30

144.01

76.18

0.39

0.53

60X60

138.44

70.61

0.37

0.49

40X40

784.95

352.51

2.11

2.28

40X40

749.15

336.86

2.02

2.21

PNT Ceramics

25X40

559.49

247.51

1.51

1.61

Golden Crown

30X30

218.62

101.85

0.53

0.66

354.56

169.22

0.95

1.14

Golden Crown Ceramics

Goodwill Super Polish NISPRO Goodwill Vitrified

Mean Value

3.2.5 The Annual Effective Dose Rate The indoors annual effective dose equivalent received by human is estimated from the indoor internal dose rate (Din), occupancy factor which is defined as the level of human occupancy in an area in proximity with radiation source; is given as 80 % of 8760 hours in a year, and the conversion factor of 0.7 Sv Gy-1 which is used to convert the absorbed does in air to effective dose (UNSCEAR, 2000). The annual effective dose equivalent is estimated using Equation 5.

AEDR  0.49C Ra  0.76CTh  0.048C K   8.76  10 3

(5)

The value of the AEDE ranges from 0.65 to 3.69 mSv y-1 with a mean value of 1.59 mSv y-1. The mean values from the samples surpass the world’s average value of 0.07 mSv y-1 by a factor 5.7. Details of all the samples are presented in Table 5. 3.2.6 Gamma Index Determination (Iγ) Gamma index is used to evaluate the γ-radiation hazard related to the natural radionuclide in the particular samples under investigation. The gamma index representation (Iγ) is estimated using Equation (6) as presented by OECD (1979). I 

C Ra

300

( Bq / kg) 

CTh

200

( Bq / kg)  C K

3000

( Bq / kg)

(6)

The estimated results are presented in Table 5. The controls on the radioactivity of building materials according to RP122 (EC, 1999) is based on the dose criterion for control and exemption. The dose effective exceeding the criterion level of 1 mSvy-1 should be taken into account for radiation protection. It recommends that controls of dose range of 0.3 to 1 mSvy-1, which is the excess gamma dose to that received outdoors. The gamma activity index is used to identify whether a dose criterion is met (EC, 1999). This gamma activity index accounts for the ways and amounts in which the materials used in building, with limit value of their indices not exceeding the recommended value and depends on the dose criterion shown in Table 5. In this present study, the dose has been calculated excluding the background dose which was shielded by the building materials when used in bulk but does not still exclude when building materials used as a superficial material. This is because the thin layers of superficial material do not reduce significantly the background dose. The gamma activity index ⦤ 1, corresponds to annual effective dose less than or equal to 1 mSvy-1, while gamma activity index ⦤ 0.5 corresponds to 0.3 mSvy-1 if the materials are used in bulk quantity. At the same time, gamma activity index ⦤6 corresponds to annual effective dose of 1 mSvy-1 and gamma activity index ⦤ 2 corresponds to an annual effective dose ⦤ 0.3 mSvy-1 if the bulk materials are used in a superficial way. In this study as shown in Table 5, the results for superficial materials such as tiles vary from 0.18 mSvy1

(Goodwill vitrified tile) to 2.79 mSvy-1 (NISPRO tile) with average value of 1.00 mSvy-1.

Building materials such as tile should be exempted from all restrictions regarding radioactivity if the excess gamma radiation emanating from them increases the annual effective dose of a

member public by 0.3 mSv at the most. Considering the criterion of unity that corresponds to annual effective of 1 mSv, all the present values are below the criterion which corresponds to the protection level except PNT ceramic (30X30), NISPRO and PNT ceramic (25X40) tiles. 3.2.7 Determination of Alpha Index (Iα) The assessment of the alpha index is another important aspect of hazard assessment that deals with the estimation of that excess alpha radiation due to radon inhalation originating from building materials. The alpha index calculated using Equation (7) (Righi and Bruzzi, 2006; Xinwei et al., 2006) is: I 

C Ra

200

( Bq / kg)

(7)

where CRa is the activity concentration of radium Bqkg-1 in building materials. If the radium activity level in building material exceeds the values of 200 Bqkg-1 there is possibility that the radon exhalation from the material could cause indoor radon concentrations exceeding Bqm-3. Table 5 presents the values for alpha index. The International Commission on Radiation protection recommends an action level of 200 Bqm-3 for radon in dwellings (ICRP, 1994). At the same time, if this radium activity level is below 100 Bqkg-1, it shows that radon exhalation from building materials may not likely cause indoor concentration greater than 200 Bqm-3 (Xinwei et al., 2006). It is reported that the recommended exempted value and the recommended upper limit for radon concentrations are 100 Bqkg-1 and 200 Bqkg-1 respectively in building materials (RPA, 2000). It is noted that the upper limit of radon concentration (Iα) is equal to 1 (Tufail et al., 2007). The results of the present study show that the radon concentration varies from 0.14 to 1.21 respectively with average value of 0.34. With this lower value, it indicates that the radon exhalation from all the analyzed samples would cause indoor concentration lower than 200 Bqkg-1.

Table 5. The Annual Effective Dose (mSv/y), Gamma activity Index (Iγ) and Alpha Index (Iα) Annual Sample Name

Sample size

Effective Dose

Gamma activity

Alpha Index

Index(Iγ)

(Iα)

(mSv/y) BN Ceramics

60X60

1.12

0.76

0.19

PNT Ceramics

30X30

1.76

1.36

1.21

25X30

0.79

0.61

0.25

Royal Ceramics

40X40

0.74

0.57

0.33

Royal Crown

30X30

0.68

0.52

0.26

60X60

0.65

0.49

0.22

40X40

3.69

2.79

0.29

40X40

2.84

0. 18

0.35

PNT Ceramics

25X40

2.61

1.97

0. 18

Golden Crown

30X30

1.03

0.79

0. 14

1.59

1.00

0.34

Golden Crown Ceramics

Goodwill Super Polish NISPRO Goodwill Vitrified

Mean Value

4. Conclusions The measurement of natural radioactivity concentration and its associated radiological risks from 10 investigated tiles samples made in Nigeria for buildings purposes were evaluated using gamma ray spectrometry. These following endpoints can be drawn: 1. The mean activity concentration of

226

Ra,

232

Th and

40

K have been found to be 68.2,

173.9 and 490 Bq/kg respectively. On the average, activity concentration of 40

and K were found to be below recommended value.

226

Ra,

232

Th

2. The radium equivalent activity for most of the tiles samples used is less than the recommended value of 370 Bq/kg set in by UNSCEAR (2000) report excluding PNT ceramic (30X30), NISPRO, Goodwill Vitrified, PNT Ceramics (25X40) tiles sample with a value of 391. 10, 784.95, 749.15 and 559.49 Bq/kg respectively. 3. The absorbed dose rate in air was found to be in the ranged of 70.61 to 352.51 nGyh-1 with mean value of 169.22 nGyh-1 which is higher than international value of 55 nGyh-1 by factors of 3.2 and 2.1 according to UNSCEAR (1998) and 80 nGyh-1 by UNSCEAR (2000) respectively. 4. The average value of Hex and Hin are 0.95 and 1.14 respectively. The mean value of Hex is lower than unity as recommended by UNSCEAR (2000) while Hin is higher. It was also observed that PNT ceramic (30X30), NISPRO, Goodwill Vitrified and PNT Ceramics (25X40) have values higher that international reference value. 5. The result of annual effective dose rate show higher value in tile samples BN ceramic, PNT ceramic (30X30 mm), BN ceramic, NISPRO, Goodwill Vitrified, and PNT ceramic (25X40) above recommended value of 1 mSv/yr as well as on the average value. 6. The mean value of gamma activity index is 1 and is still within the world recommended value and the Alpha Index (Iα) is 0.34. From the result above, it shows that the tiles sample such as PNT ceramic (30X30), NISPRO, Goodwill Vitrified and PNT Ceramics (25X40) should be monitored before usage for building purposes. 7. The higher values of NISPRO produced along Abuja-Kaduna express way could be attributed to the nature of the basement complex of the Pan-African Orogeny of the sourced raw material of the granitic rock materials. Goodwill vitrified and PNT ceramics (25 x 30 mm) may be attributed to the marine transgression and regression of metamorphosed sediments from far and near granitic tectonically and highly dissolved rock minerals in and round the Atlantic Ocean in Lagos.

Acknowledgements The researchers appreciate Covenant University center for Research, Innovation and Discovery Ota for 100 % financial supports to embark on this research for the safety of our nation.

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Highlights  Concentrations of the natural radionuclides 226Ra, 232Th, and 40K were measured.  10 tile samples of different brands have been analyzed using Gamma ray spectroscopy.  Activity concentrations in Bq/kg were determined using a High purity Germanium detector.  Radiological hazard indices such Raeq, Dr, AEDE, Hex, Hin, Iγ and Iα were evaluated.